This project area studies immunological responses in humans with periodontal disease. Clinically characterized subjects provide peripheral blood leukocytes (PBL) for study of blastogenic responses to oral bacterial sonicates & mitogens including plaquing assay, and the kinetics of unstimulated blastogenesis. Serum antibody is studied by gel diffusion and radioimmunoassay. Studies to determine the relative roles of the B- and T-cells in the responses to the bacterial preparations have been initiated, as have studies to elucidate the mitogenicity of these preparations. Cryopreservative methods for storing PBL have been developed and are in use for many of the studies. Interactions of several bacterial sonicates in PBA experiments are being studied. We have demonstrated PBA activity in many oral bacterial sonicates, both gram-positive and gram-negative. Both inhibition and synergy can be demonstrated in combinations of sonicates. Normal control subjects' PBL respond in blastogenesis experiments and PBL from subjects with several periodontitis populations also respond but not to a significantly different degree. There seems to be a significant component of mitogenesis in these experiments and B-cells are the major responder cells early (2-4 days), T-cells late (5-7 days). Results from unstimulated cultures of PBL indicate a defective autologous mixed lymphocyte reaction in severe periodontitis of young adults. Preliminary data indicate this may be reversed by periodontal treatment. High levels of serum antibody, detectable by gel diffusion, to Actinobacillus actinomycetemcomitans are found in most individuals with juvenile periodontitis, slightly less than half of those with severe, generalized periodontitis in young adulthood, and very few periodontally normal persons. Among those with the severely destructive periodontal conditions, progress of disease seems to have been ameliorated in those with the antibody compared to those in whom the antibody is not detectable by gel diffusion. In addition to continuing these studies, we plan to initiate study of T-cell subsets in periodontally diseased persons.